The diffracted pattern was precisely imprinted in the film in the form of concentric circles of spheroidal nanoparticles having dimensions between 5 and 100 nm. The geometrical characterization of the nanostructures and nanoparticles was performed by transmission electron microscopy and atomic force microscopy. Furthermore the observed effects can be explained using Fresnel diffraction theory, suggesting that precise patterning engineering can be performed through the control of spatial parameters such as the pinhole diameter and the distance from the mask to the sample.

Fast and simple technique

The whole process takes place in a few nanoseconds, generating simultaneously micron and submicron patterning in the surface of the film. The deposition in a vacuum chamber and patterning in air of the samples are realized with the same laser.

"The various applications we have in mind include high-density storage media and patterned surface enhanced Raman spectroscopy (SERS) substrates. Patterning of larger surfaces could be achieved by controlling the mask and by using piezoelectric devices to move the sample," Emmanuel Haro-Poniatowski told "From a fundamental point of view, it is very important to understand the thermodynamic mechanisms that determine the final size of the nanoparticles. This information will help us to design strategies to control the size distribution of the nanoparticles".

The researchers presented their work in the journal Nanotechnology.